1) Durability: how long a string can whitstand hitting until it breaks/snaps
2) Playability Duration: how long a string maintains consistent playing characteristics (e.g. power, feel, softness, spin potential etc.)

Dragan is pretty spot on with his explanation. The durability is in reference to how long the string will last before breakage.

The playability duration is an especially important factor when considering polyester strings because of their nature. While the durability may keep the strings in your racquet longer, the playability duration is the expected life of the "feel" of the strings. Even though you can keep RPM in your racquet for a long time before it breaks, it doesn't mean that the expected performance qualities of the string will still be there after the playability duration has passed (which is why a lot of people can become disappointed with Polys and Co-Polys after roughly 2 weeks).

If your strings lose tension before you break them, then continuing to play with the strings can have ill effects (elbow pain, no power, etc...). If you break polyester strings before they lose tension and feel, then you may need to consider a more durable string.

The rest of the crew may chime in and offer tips too, but there are a variety of reasons, or indicators, of when it's time to change your string.

Many players will describe their poly strings as feeling "dead" (when initially they felt very "lively") after a few weeks of using it. This is a big indicator that your strings aren't holding their tension and are causing you to do more work to achieve the same results. Even though the string is still useable, this extra work can cause arm aggravation.

There are also tools that, when used properly (extra emphasis here), can measure the total stringbed tension over the life of the string. http://www.tennis-warehouse.com/desc...PCODE=STRMETER The tension that is read will typically be lower than the tension at which it was originally strung, but it will provide information on how much tension your racquet is losing over time.

Again, these are just some suggestions but we hope they help you in the future.

The rest of the crew may chime in and offer tips too, but there are a variety of reasons, or indicators, of when it's time to change your string.

Many players will describe their poly strings as feeling "dead" (when initially they felt very "lively") after a few weeks of using it. This is a big indicator that your strings aren't holding their tension and are causing you to do more work to achieve the same results. Even though the string is still useable, this extra work can cause arm aggravation.

There are also tools that, when used properly (extra emphasis here), can measure the total stringbed tension over the life of the string. http://www.tennis-warehouse.com/desc...PCODE=STRMETER The tension that is read will typically be lower than the tension at which it was originally strung, but it will provide information on how much tension your racquet is losing over time.

Again, these are just some suggestions but we hope they help you in the future.

This customer's feedback is quite a common reaction with these string tension measurement devices. While these devices are intended to give you quantifiable measurements, they will not tell you the tension at which the racquet was strung (which is why I put extra emphasis on "proper use" of the device, which can be very subjective).

These measurement devices are merely to give you a reading of "stringbed stiffness," not "reference tension" which is the tension you set on your stringing machine. Stringbed stiffness will always be lower than your reference number.

As far as the difference between the reviewer's tension meter and his friend's, there are many many factors that can lead to this difference.

The main goal of these devices is so that a player can identify tension loss over the life of the string because the strings are constantly losing tension.

I hope this is helpful, as I know it can be very subjective and difficult to explain.

This customer's feedback is quite a common reaction with these string tension measurement devices. While these devices are intended to give you quantifiable measurements, they will not tell you the tension at which the racquet was strung (which is why I put extra emphasis on "proper use" of the device, which can be very subjective).

These measurement devices are merely to give you a reading of "stringbed stiffness," not "reference tension" which is the tension you set on your stringing machine. Stringbed stiffness will always be lower than your reference number.

As far as the difference between the reviewer's tension meter and his friend's, there are many many factors that can lead to this difference.

The main goal of these devices is so that a player can identify tension loss over the life of the string because the strings are constantly losing tension.

I hope this is helpful, as I know it can be very subjective and difficult to explain.

Aaron
TW Customer Service.

Hi,
is it possible to evaluate tension meter vs poly strings used by a tester?
I did it multiple times failing all the time.
I coach high school tennis and I should recommend setups
(my credentials can be checked via my signature)
Some of my students buy strings from you
regards,
Julian

The best and most reliable use of the devices is when the same device is used over the period of several string jobs on the same racquet with the same string and tension. There would not be a repeatable way to compare the results if ANY of these factors are changed, especially the measurement device.

Using this device to make recommendations to a player would only be helpful if you have been monitoring that players string conditions over an extended period of time.